AU2010345651B2

AU2010345651B2 - Phenolic Resin Adhesive Composition

Info

Publication number: AU2010345651B2
Application number: AU2010345651A
Authority: AU
Inventors: Peiqiang Li; Caixia Ma; Jianxun Zhu
Original assignee: Jinan Shengquan Group Share Holding Co Ltd
Current assignee: Jinan Shengquan Group Share Holding Co Ltd
Priority date: 2010-02-11
Filing date: 2010-02-11
Publication date: 2013-11-28
Anticipated expiration: 2030-02-11
Also published as: RU2011134668A; TR201108926T1; RU2480308C1; CN102753619B; CN102753619A; WO2011097818A1; AU2010345651A1

Abstract

A phenolic resin binder composition comprises alkaline phenolic resin, first alkaline and hardening accelerator, which is characterized by (the fact) that the alkaline phenolic resin is produced by bisphenol A instead of parts of phenol, and the molar ratio of bisphenol A to phenol is in the scope of 1:10~25. The binder composition can be used as cold core-box materials in casting industry. The present binder composition can improve moisture resistance and high-temperature strength of molds and cores in storage after gases passing them.

Description

1 PHENOLIC RESIN ADHESIVE COMPOSITION FIELD OF THE INVENTION 5 The present invention relates to a phenolic resin adhesive composition and use of the same in producing an adhesive particle material composition, e.g. a mold and a mold core material. BACKGROUND TO THE INVENTION 10 A C02 cured phenolic resin binding agent, composed of a A stage phenolic resin with a high hydroxymethyl content, alkali, hardening accelerator, modifier, etc., is currently the most promising binding agent in the foundry industry due to its non-toxicity and favorable environmental advantage, wherein the A stage 15 phenolic resin, a main component of the binding agent, is yielded by a polycondensation reaction of phenol and formaldehyde under the presence of an alkaline catalyst. The alkali in the binding agent acts to reduce viscosity, viz. serving as a dispersant. Currently, the alkali regarded as the best choice is KOH, the reason for which is that a resin solution prepared by KOH has a lower 20 viscosity as compared with NaOH and LiOH. The current C02 cured alkaline phenolic resin binding agent still has its drawbacks in terms of mold application, for example, the cast mold and mold core have a relatively low strength, viz. a high-moisture strength and a high 25 temperature strength, causing the defects such as the damage of the mold and the mold core in use as well as the cuts and heat cracks of castings. These drawbacks will negatively affect the application range of the mold and the mold core.

2 SUMMARY OF THE INVENTION The object of the present invention is to provide a novel C02 cured 5 phenolic resin adhesive composition for manufacturing a mold to enhance the property of anti-moisture absorption of the mold. Another object of the present invention is to adjust the curing speed of the resin in the adhesive and to improve the strength of the adhesive. 10 The present invention, therefore, provides an alkaline phenolic resin adhesive composition comprising an alkaline phenolic resin, a first alkali, and a hardening accelerator, wherein the alkaline phenolic resin is prepared by substituting a part of phenol with bisphenol A, and the molar ratio of bisphenol A 15 to phenol is in the range of 1:10 to 1:25, preferably 1:15 to 1:20. In one preferred embodiment, the first alkali is composed of potassium hydroxide and sodium hydroxide, wherein the molar ratio of the sum of potassium hydroxide and sodium hydroxide to phenol is in the range of 1.5:1 to 2.5:1. 20 Preferably, the molar ratio of potassium hydroxide to phenol is in the range of 0.5:1 to 2.5:1, and the molar ratio of sodium hydroxide to phenol is in the range of 0.1:1 to 2.0:1. The composition of the present invention may further comprising 1 to 20% 25 by weight of an additive, which is selected from a group consisting of cyclic ether, phenylglycol methyl ether, glycerol ether, ethylene glycols alkyl ether, and propylene glycols alkyl ether. Preferably, adding polyhydric alcohols or carbohydrate to the adhesive can 30 increase the amount of groups participating in a complexing reaction and raise the binding strength of the adhesive. These compounds contain active hydroxyls, which undergo a polymerization reaction there between or undergo a crosslinking reaction with a resin. Gel generated from this crosslinking reaction is an 2a irreversible gel, which greatly increases the binding strength of the adhesive. Ethylene glycols and propylene glycols polyhydroxy compounds may undergo a complexation reaction with boric acid and borate ions. 5 Another aspect of the present invention relates to an alkaline phenolic resin adhesive composition containing an alkaline phenolic resin, a first alkali, and a hardening accelerator, wherein the first alkali is composed of potassium hydroxide and sodium hydroxide, and the molar ratio of the sum of potassium hydroxide and sodium hydroxide to phenol is in the range of 1.5:1 to 2.5:1. 10 Preferably, the molar ratio of potassium hydroxide to phenol is in the range of 0.5:1 to 2.5:1, and the molar ratio of sodium hydroxide to phenol is in the range of 0.1:1 to 2.0:1. A hardening accelerator can be added to said composition, which can be 15 selected from a group consisting of borates, stannates, and aluminates. Borax of the borates is a priority choice due to its property and cost. Substituting a part of phenol with bisphenol A to synthesize a phenolic resin adhesive can enhance the property of anti-moisture absorption of the mold 20 and the core being stored after passage of air, facilitate long-time storage in a damp environment, improve the strength of the mold core which has dried after being brushed with a water-based coating, and increase the high-temperature strengths of the mold and the core being stored after passage of air. Water is added to reduce the viscosity of the resin, which is beneficial for uniformly mixing. 25 An aspect of the present invention provides an phenolic resin adhesive composition, including an alkaline phenolic resin, alkali, and a hardening accelerator; wherein the alkaline phenolic resin is prepared by substituting a part of phenol with bisphenol A, and the molar ratio of bisphenol A to phenol is in the 30 range of 1:15 tol: 20; the alkali is composed of potassium hydroxide and sodium hydroxide, and the molar ratio of the sum of potassium hydroxide and sodium hydroxide to phenol is in the range of 1.5:1 to 2.5:1; the molar ratio of potassium 2b hydroxide to phenol is 0.5:1 to 2.5:1, and the molar ratio of sodium hydroxide to phenol is in the range of 0.1:1 to 2.0:1 DESCRIPTION OF PREFERRED EMBODIMENT 5 On a first aspect of the present invention, bisphenol A is introduced in raw materials for preparing a phenolic resin. The molar ratio of bisphenol A to phenol may be in the range of 1:10 to 1:25, preferably in the range of 1:15 to 1:20. The inventor has found that, in comparison with the case of using phenol alone, 10 substituting a part of phenol with bisphenol A can improve plural properties of the cast mold. Specifically speaking, the property of anti-moisture absorption of the mold (sand mold and mold core) is enhanced, thereby the mold can be stored for a long time in a damp environment and the core strength is slightly affected after the mold is brushed with a water-base coating and dries; and the compression 15 strength of the mold which is passed by a C02 gas and stored for a period of time at high temperature (e.g. 100 to 200 *C) is enhanced and the collapsibility thereof at high temperature is improved. In the present invention, the raw materials for preparing the phenolic resin 20 comprise phenol, optional bisphenol A, alkali (a second alkali), formaldehyde, and water. In cases that 25 bisphenol A is not introduced, the molar ratio of formaldehyde to phenol is suitably in the range of 1.75 to 2.3. When one mole of bisphenol A is introduced, the amount of phenol can be reduced by two moles accordingly. In actual production, paraformaldehyde is usually used as a source of formaldehyde. At this time, the molar amount of formaldehyde is calculated according to the molar amount of formaldehyde monomer in paraformaldehyde. The second alkali can be selected from a group consisting of Na 2

CO

3 , NAOH, KOH, and aqueous ammonia, and the amount thereof can be a typical amount in the prior art, and the molar ratio of the second alkali to phenol may be 0.02 to 0.15. After the phenolic resin has been prepared, other components of the composition are mixed with the resin. The other components include a hardening accelerator, a first alkali, and an optional additive. The hardening accelerator mainly comprises oxacid salts, such as berates, stannates, aluminates, and titanates. The first alkali may be sodium hydroxide, potassium hydroxide, or lithium hydroxide. In one preferred embodiment of the present invention, different from the usage of a single type of the first alkali in the prior art, a combination of sodium hydroxide and potassium hydroxide is used as a viscosity modifier for the adhesive. In this case, the molar ratio of potassium hydroxide to phenol is preferably 0.5:1 to 2.5:1, the molar ratio of sodium hydroxide to phenol is preferably 0.1:1 to 2.0:1, and the molar ratio of the sum of potassium hydroxide and sodium hydroxide to phenol is in the range of 1.5:1 to 2.5:1 which can be flexibly adjusted upon the specific requirements of the product. The inventor has found that the resin, with potassium hydroxide used alone, has a relatively fast curing speed and a high initial strength; however, its final strength after 24 hours is relatively low. After the sodium hydroxide is added to be substituted for partial potassium hydroxide, the curing speed is slowed down, and the initial strength is lowered, but the final strength after 24 hours is remarkably improved. If the product is expected to have a high initial strength but no requirement for the final strength, sodium hydroxide may not be used. If the final strength of the product is expected to be increased, sodium hydroxide may be used in an amount of no more than twice as much as the molar amount of phenol. The inventor has also found that, with the increase in the amount of sodium hydroxide used, the final strength of the product is correspondingly increased. However, the excessive amount of sodium hydroxide used causes the resin to be cured very slowly, consumes excessive carbon dioxide gas, and decreases the efficiency of producing the mold core. Therefore, in the present invention, the required initial strength and final strength can be adjusted flexibly by the combination of sodium hydroxide with potassium hydroxide. The first alkali and the second alkali in the present invention are used in the form of an aqueous solution, and are prepared to have a concentration of 20 to 50 wt%. An additive may also be introduced for the composition of the present invention so as to improve the properties of the resin sand, such as strength, surface stability, anti-moist capacility. The amount of the additive generally does not exceed 20% of the weight of the composition, Ethers compounds are usually used in the prior art to improve the strength and the surface stability of the sand mold (core), the flowability of the resin sand, and minimize the pores. These ethers compounds mainly include cyclic ether, phenylglycol methyl ether, glycerol ether, ethylene glycols alkyl ether, and propylene glycols alkyl ether, The water-soluble high-molecular 3 compounds of carbohydrate, aliphatic dibasic acid or aliphatic tribasic acid, aliphatic diamines or aliphatic triamines, aliphatic diamide or aliphatic triamide, etc. may also be added. These compounds can increase the content of groups participating in the complexing reaction and raise the binding strength of the adhesive. A silane coupling agent may also be used in said adhesive composition. The silane coupling agent can improve effectively the attachment strength of the adhesive to sand grains and reduce the attachment breakage of the resin sand. The silane commonly used in the prior art comprises triamino propyl trimethoxysilane, N-(2-aminoethane)-3-aminopropyltrimethoxysilane, phenyltrimethylsilane or triglycidyl ether propyl trimethoxysilane The above preferable characteristics of the present invention can be used separately. Embodiment 1 The alkaline phenolic resin can be synthesized using the following components: Phenol 900.0og Bisphenol A 121.44g 92% paraformaldehyde 693.80g 48% aqueous potassium hydroxide solution 135g Formaldehyde to phenol(molar) 20: 9 Formaldehyde to bisphenol A(molar) 40: 1 Potassium hydroxide to formaldedyde(molar) 0,05:1 The phenolic resin is prepared according to the following process: taking phenol and melting it; adding bisphenol A and melting; adding the potassium hydroxide solution by drops, cooling for neutralizing an exothermal reaction and heating at a rate of 1*C per minute to 65 to 70'C; cooling for neutralizing the exothermal reaction and maintaining the temperature in the range of 65 to 70 "C by continuously adding paraformaldehyde within one to two hours; heating at a rate of 1'C per minute to 85"C; and maintaining the temperature at 85"C for a sufficient period of time to enable the resin viscosity to reach 200 to 500mPa.s, and at 25C, measuring out 50g of the sample and diluting it in 65g of the 48 wt% potassium hydroxide solution, and revolving a viscometer for measurement. Said resin is used to produce 183g of a basal adhesive, and reconstitute based on the 4 weight proportions in Table 1. Table 1 Resin Potassium Sodium Lithium Borax Ethylene glycol Water hydroxide hydroxide hydroxide (g) monomethyl ether 48% (g) 35% (g) 20.5% (g) (g) Embodiment 1-1 173.58 69.27 0 33.84 37.44 60 Embodiment 1-2 248.81 0 0 33.84 37.44 60 Embodiment 1-3 93.51 155.3 0 33.84 37.44 60 Embodiment 1-4 93.51 0 155.3 33.84 37.44 60 Embodiment 1-5 173.58 69.27 0 33.84 37.44 0 Embodiment 1-6 173.58 69.27 0 33.84 37.44 30 Embodiment 1-7 173.58 69.27 0 33.84 0 60 Embodiment 1-8 173.58 69.27 0 33.84 18.72 60 The above resin contains N-(2-aminoethane)-3-aminopropyltrimethoxysilane which is 1.0% of its total weight. The potassium hydroxide and sodium hydroxide solutions are added to the resin for controlling the heat release and the increase of the reaction temperature, such that the temperature is maintained at 60"Cand the resin is cooled. Borax is added and mixed with the resin until it is decomposed. The addition of silane shall be performed below 40'C. Embodiment 2 The alkaline phenolic resin can be synthesized using the following components: Phenol 1000.0Og 92% parafonnaldehyde 693.80g 48% aqueous potassium hydroxide solution 135g Formaldehyde to phenol(molar) 2.0: 1 Potassium hydroxide to formaldedyde(molar) 0.05:1 The phenolic resin is prepared according to the following process: 5 taking phenol and melting it; adding the potassium hydroxide solution by drops, cooling for neutralizing an exothermal reaction and heating at a rate of 1*C per minute to 65 to 70"C; cooling for neutralizing the exothennal reaction and maintaining the temperature in the range of 65 to 70 *C by continuously adding paraformaldehyde within one to two hours; heating at a rate of 1C per minute to 85"C; and maintaining the temperature at 85"C for a sufficient period of time to enable the resin viscosity to reach 200 to 5OOmPa.s, and at 25C, measuring out 50g of the sample and diluting it in 65g of the 48 wt% potassium hydroxide solution, and revolving a viscometer for measurement. Said resin is used to produce 183g of a basal adhesive, and reconstitute based on the weight proportions in Table 2. Table 2 Resin 48% Potassium 35% 20.5% Borax Ethylene Water hydroxide Sodium Lithium glycol hydroxide hydroxide monomethyl ether Embodiment 2-1 173.58 69.27 0 33.84 37.44 60 Embodiment 2-2 248.81 0 0 33.84 37.44 60 Embodiment 2-3 93.51 155.3 0 33.84 37.44 60 Embodiment 2-4 93.51 0 155.3 33.84 37,44 60 Embodiment 2-5 173.58 69.27 0 33.84 37.44 0 Embodiment 2-6 173.58 69.27 0 33.84 37.44 30 Embodiment 2-7 173.58 69.27 0 33.84 0 60 Embodiment 2-8 173.58 69.27 0 33.84 18.72 60 The above resin contains N-(2-aminoethane)-3-aminopropyltrinethoxysilane which is 1.0% of its total weight. The potassium hydroxide and sodium hydroxide solutions are added to the resin for controlling the heat release and the increase of the reaction temperature, such that the 6 temperatures is maintained at 60"C and the resin is cooled. Borax is added and mixed with the resin until it is decomposed. The addition of silane shall be performed below 40'C. Embodiment 3-6 The alkaline phenolic resin can be synthesized using the following components in accordance with the method of Embodiment 1: Table 3 Component Embodiment 3 Embodiment 4 Embodiment 5 Embodimen t 6 Phenol 833.3 925.9 882.4 909.1 Bisphenol A 193.3 89.8 142.7 110.3 92% paraformaldehyde 693.80g 693.80g 693.80g 693.80g 48% potassium 135g 135g 135g 135g hydroxide Phenol/ bisphenol A 10 : 1 25 : 1 15 :1 20 : 1 (M/M) fonnaldehyde/potassium 0.05 : 1 0.05 : 1 0.05 : 1 0.05 : 1 hydroxide (M/M) 183g of the basal adhesive produced above are used to reconstitute based on the weight proportions in Table 4. Table 4 Resin Potassium Sodium Lithium Borax Ethylene glycol Water hydroxide hydroxide hydroxide (g) monomethyl ether 48% (g) 35% (g) 20.5% (g) (g) Embodiment 3 173.58 69.27 0 33.84 37.44 60 Embodiment 4 173.58 69.27 0 33.84 37.44 60 Embodiment 5 173.58 69.27 0 33.84 37.44 60 Embodiment 6 173.58 69.27 0 33.84 37.44 60 Embodiment 7 7 The adhesive of the above embodiment is mixed with Dalin silica sand (50 to 100 mesh). The amount of the adhesive used is 3 wt% of the silica sand. The mixture is used to fabricate the standard AFS 50mrnx50mm cylindrical cast core. Under the conditions that the temperature of the sand is 18.6"C, the pipeline pressure is 0.20kg/cm 3 , and the flow rate is 5,0 L per minute, a carbon dioxide gas is constantly aerated, such that the cast core becomes hardened and cured. After being aerated, some cast cores are instantly tested on a universal high-force device of a hydraulic strength testing machine (Model No.: SWY), some cast cores are tested after being stored for 24 hours in a dry-storage condition (the temperature is 18 to 20E] and the relative humidity is 40 to 55%), some cast cores are tested after being stored for 24 hours in a high-humidity storage condition (the temperature is 18 to 20"C and the relative humidity is 95 to 99%), and some cast cores are cooled to room temperature for testing after being stored for 24 hours in a dry-storage condition and then for 30 minutes in a drying oven at 140'C. The testing results are as shown in Table 5. Table 5 Resin CO 2 aeration time 30 CO 2 aeration time 60 seconds seconds Compression strength Mpa Compression strength Mpa instantly 24H instantly 0.5H 24H 24H high drying at 140"C humidity for 30min Embodiment 1-1 1.20 3.20 1.30 2.30 3.50 2.80 4.90 Embodiment 1-2 1.50 2.70 1.60 2.50 3.00 1.90 4.40 Embodiment 1-3 0.70 3.20 1.10 2.00 3.90 2.90 5.60 Embodiment 1-4 1.10 3.30 1.50 2.20 3.30 2.70 5.20 Embodiment 1-5 1.20 3.50 1.70 2.50 3.80 3.00 6.00 Embodiment 1-6 1.30 3.50 1.50 2.50 3.80 2.90 6.10 Embodiment 1-7 1.10 2.80 1.20 2.20 3.20 2.30 4.10 Embodiment 1-8 1.40 2.60 1.60 2.40 3.10 2.40 4.20 Embodiment2-1 1.10 3.10 1.40 2.10 3-40 2.30 4.10 Embodiment 2-2 1.40 2.70 1.70 2.20 2.80 1.50 3.90 Embodiment 2-3 0.70 2.90 1.20 1.80 3.80 2.50 5.20 Embodiment 2-4 1.10 3.00 1.60 2.30 3.40 2.20 4.50 Embodiment 2-5 1.40 3.30 1.80 2.50 3.70 2.70 4.70 Embodiment 2-6 1.20 3.50 1.40 2.60 3.80 2.60 4.90 Embodiment 2-7 1.00 2.50 1,20 2.00 2.70 2.10 3.10 Embodiment 2-8 1.30 2.80 1.50 2.40 3.00 2.10 3.50 Embodiment 3 0.65 2.62 1.05 1.85 2.90 2.45 5.50 Embodiment 4 1.30 2.30 1.45 2.15 3.30 2.40 4.20 Embodiment 5 1.10 3.10 1.25 2.30 3.45 2.90 5.10 Embodiment 6 1.25 3.30 1.40 2.4 3.55 2.85 4.85 8 A carbon dioxide gas is aerated to effectuate a neutralization reaction with the alkali of the resin, such that the PH of the resin is lowered, the dissolution equilibrium of the initially stable resin solution is changed, and the heat is released. Under the effect of the hardening accelerator, the resin is gel cured, and the strength of the cast core is immediately improved. In Table 6, the average compression strength of Embodiments 1-1 to 1-8 is compared with that of Embodiments 2-2 to 2-8. The results show that, the high-moisture and high-temperature strengths demonstrated in Embodiment 1 in which bisphenol A is used for modification are greatly improved in comparison with those demonstrated in Embodiment 2 in which phenol is used alone. Table 6 Resin Average compression strength Mpa after CO 2 aeration time 60 seconds 24H 24H high-humidity drying at 140"C for 30min Embodiments 1-1 to 3.45 2.61 5.57 1-8 average Embodiments 2-2 to 3,33 2.25 4.24 2-8 average Based on the resulting strengths of Embodiments 1-1 and 1-7 and Embodiments 2-1 and 2-7, it is shown that after the adhesive is added to ethylene glycol monomethyl ether, the 24H, high-moisture, and high-temperature compression strengths of the tested sample are enhanced, indicating that using the additive after the cast core is stored can also achieve a good effect. Based on the resulting strengths of Embodiments 1-1, 1-2, and 1-3 and Embodiments 2-1, 2-2, and 2-3, it is shown that the addition of potassium hydroxide accelerates the curing speed of the resin and the addition of sodium hydroxide will increase the 24-hour strength of the resin. The combination of the two in a certain proportion can meet ideal usage requirements. Based on the resulting strengths of Embodiments 1-1, 1-5, and 1-6 and Embodiments 2-1, 2-5, and 2-6, it is shown that reducing the amount of water added to the adhesive or no water added might raise the instant and 24-hour strengths of the resin in a certain range, however, too small amount of water will causes resin viscosity too high, such that the sand is mixed non-uniformly, the flowability and the filling ability of the resin sand are decreased, and thus the strength and the functional performance thereof are weakened. Based on the resulting strengths of Embodiments 1-1, 1-2, 1-3, and 1-4 and Embodiments 2-1, 2-2, 2-3, and 2-4, it is shown that the use of lithium hydroxide does not improve remarkably the strength of the adhesive but increases the production cost in actual application, and thus lacks economical benefits, From the resulting strengths of Embodiments 3, 4, 5, and 6, it can be shown that bisphenol A in Embodiment 3 is added in a larger amount. With the same prescribed viscosity is achieved, 9 the polymerization with formaldehyde is less sufficient due to larger molecular weight of bisphenol A, causing the decrease in the curing speed and the 24H final strength of the resin; the amount of bisphenol A added in Embodiment 4 is relatively small, such that the effect is not so obvious and the high-moisture and high-temperature strengths of the resin are increased to a smaller extent; and the amounts of bisphenol A added in Embodiments 5 and 6 allow the high-moisture and high-temperature strengths of the resin to be increased within an ideal range. Part of phenol is substituted with bisphenol A for synthesizing, which can enhance the property of anti-moisture absorption of the mold and the core being stored after passage of air, facilitate long-time storage in a damp environment, improve the strength of the mold core which has dried after being brushed with a water-based coating, and enhance the high-temperature strengths of the mold and the core being stored after passage of air. Water is added to reduce the viscosity of the resin, which is beneficial for uniformly mixing, 10

Claims

1. An phenolic resin adhesive composition, including an alkaline phenolic resin, alkali, and a hardening accelerator; wherein the alkaline phenolic resin is prepared by substituting a part of phenol with bisphenol A, and the molar ratio of 5 bisphenol A to phenol is in the range of 1:15 to 1: 20; the alkali is composed of potassium hydroxide and sodium hydroxide, and the molar ratio of the sum of potassium hydroxide and sodium hydroxide to phenol is in the range of 1.5:1 to

2.5:1; the molar ratio of potassium hydroxide to phenol is 0.5:1 to 2.5:1, and the molar ratio of sodium hydroxide to phenol is in the range of 0.1:1 to 2.0:1. 10 2. The composition according to Claim 1, further including 1 to 20% by weight of an additive, which is selected from a group consisting of cyclic ether, phenylglycol methyl ether, glycerol ether, ethylene glycols alkyl ether, and propylene glycols alkyl ether.

3. The composition according to Claim 2, further including one or more water 15 soluble high-molecular compounds selected from polyol, carbohydrate, aliphatic dibasic acid or aliphatic tribasic acid, aliphatic diamines or aliphatic triamines, and aliphatic diamide or aliphatic triamide.

4. The composition according to Claim 3, wherein the polyol is ethylene glycol or propylene glycol. 20 JINAN SHENGQUAN GROUP SHARE-HOLDING CO. LTD 25 WATERMARK PATENT & TRADE MARK ATTORNEYS P34902AU00